In response to a need for energy conservation, there is a need for installing thicker insulation batts to reduce both heat loss in winter and heat gain in summer. Unfortunately, thick cathedral ceiling insulation tends to obstruct, and even close off, the ventilation spaces between roof supporting rafters, which can lead to poor air circulation under the roof.
Providing ventilation spaces between rafters can also help reduce the roof deck temperature to lessen damage to the roof deck and roofing shingles that can result from a build-up of heat to excessive levels in the summer, as well as, the build up of heat during the daylight in winter to melt snow and ice, followed by freezing temperatures that produce ice dams and roof leaks. Roof ventilation is required by most building codes and by shingle manufacturers to validate product warranties.
Quality building construction includes, vented soffits that are substantially unobstructed by insulation, and vented open spaces between rafters that are substantially unobstructed by insulation. Proper ventilation often includes an intake of ambient air through the soffits, and continuing the passage of the ambient air along the open spaces between adjacent rafters, to vent or discharge the build-up of excess humidity, condensation and heat, the presence of which are known to hasten the deterioration of roofing materials and structural components.
Venting moisture adequately from under a roof is particularly a problem for insulated cathedral ceilings, in which the roof supporting rafters double, also serve, as the ceiling joists for supporting the ceiling of an interior space of a building. Batt-type insulation mats having a sufficient R-value thickness are customarily inserted between spaced-apart rafters in cathedral ceilings to insulate the ceilings. Unfortunately, the thick insulation tends to fill the spaces between the rafters, from the ceiling below to the roof sheathing above, and thereby, tends to block ventilating air flow under the roof. Further, although most fibrous insulation mat have a vapor barrier on their interior facing surfaces, moisture from inside a building can pass through open seams and accumulate behind the vapor barrier. Moisture can also bypass the vapor barrier by traveling along skylights, wiring, plumbing and HVAC ducts.
In order to keep cathedral ceiling cavities open, and thereby provide a channel for air flow, baffled vent chutes have been installed above the insulation to promote ventilation. Prior to the present invention, vented cathedral ceilings were often built in a time consuming two-step application process. The installer first placed baffled vent chutes to extend between the rafters, from the eaves to the vented roof ridge, or peak, and stapled the baffled vent chutes to the roof sheathing that was exposed between the roof rafters. Then, batt insulation was installed between the rafters, while the baffled vent chutes held the insulation away from the under surface of the roof. Each baffled vent chute created a maintainable open channel for the passage of ventilating air for venting heat and moisture from the underside or bottom of the roof sheathing.
There is a need, therefore, for an insulation product that reduces installation complexity. Still further, there is a need for an insulation product that promotes ventilation of a space under a roof. Still further, there is a need for an insulation product having an integral baffle and a vapor permeable membrane for venting moisture into a maintainable channel of the baffle for ventilating a space between roof supporting rafters.